Biomedical Engineering Reference
In-Depth Information
Modification of carbon nanotubes (CNTs) with metal
nanoparticles (NPs) to obtain nanohybrids opens new possibilities
in their applications for catalysis. The studies on CNTs decorated
with NPs were focused on tuning the size and the distribution of
NPs [85, 86]. Integrated NPs-CNTs materials have been synthesized
by several chemical and physical methods involving chemical vapor
deposition and laser ablation [87-89]. It was found, however, that
in these methods the size and particle distribution were difficult
to control. Recently, Hong and coworkers applied ionic liquids
into the synthesis of CNT-nanohybrids [90]. They developed an
IL-assisted sonochemical method (ILASM) by which it is possible
to fabricate nanohybrids with controlled integration of NPs
(e.g., Pt, Au, and Pd). The multiwalled carbon nanotubes (MWNTs)
were
]. The IL is
self-assembled by π-π stacking interaction onto the MWNTs
and acts as active sites for NPs. In Fig. 3.6, the synthesis process
is presented. After mechanical grinding the NP precursors are
interacting with BF
mixed
and
grinded
with
[BMIM][BF
4
anions and after sonication the NPs are
deposited onto the surface of MWNTs. The most important finding
was the fact that the size and distribution of the used particles
can relatively easy be controlled by changing the sonication time
and the precursor concentration.
An interesting approach in generation of graphene sheets from
graphite electrode was presented by Liu et al. [91]. The synthesis
was conducted in ionic liquid environment. In the past, carbon
nanoparticles have been exfoliated from graphite mainly by laser
ablation [92] or by electrochemical methods [93]. ILs may be a
promising and inexpensive alternative to make graphene sheets. The
method developed by Liu et al. [91] is a one-step process and can
be used in large-scale production of graphene. They used a mixture
containing [BMIM][PF
-
4
] and 10 mL of water and a potential of
15 V was applied between the two graphite electrodes (Fig. 3.7). The
resulting precipitate consisted of exfoliated graphene sheets of ca.
500 nm in size. This method has the advantage over the chemical
method to produce graphene films from graphene oxide derivatives
due to the fact that it provide less defects, hence resulting in the
increase in charge carrier mobility [94].
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